scholarly journals Earthquake Seismic Moment, Rupture Radius and Stress-drop from P-wave Displacement Amplitude vs Time Curves

2021 ◽  
Author(s):  
aldo zollo ◽  
sahar nazeri ◽  
Simona Colombelli
Keyword(s):  
Stress Drop ◽  
Seismic Moment ◽  
Central Italy ◽  
Average Stress ◽  
Displacement Amplitude ◽  
P Wave ◽  
Parametric Modelling ◽  
Peak Displacement ◽  
Reliable Determination ◽  
Anelastic Attenuation

The reliable determination of earthquake source parameters is a relevant task of seismological investigations which ground nowadays on high quality seismic waveforms collected by near-source dense arrays of ground motion sensors. Here we propose a parametric modelling technique which analyzes the time-domain P-wave signal recorded in the near-source range of small-to-large size earthquakes. Assuming a triangular moment-rate function and a uniform speed, circular rupture model, we develop the equations to estimate the seismic moment, rupture radius and stress-drop from the corner-time and plateau level of the average logarithm of the P-wave displacement vs time curves (LPDT). The constant-Q, anelastic attenuation effect is accounted by a post-processing procedure that evaluates the Q-unperturbed moment-rate triangular shape.<br>The methodology has been validated through the application to the acceleration records of the 2016-2017 Central Italy and 2007-2019 Japan earthquake sequences covering a wide moment magnitude range (Mw 2.5 - 6.5) and recording distance < 100 km. After correcting for the anelastic attenuation function, the estimated average stress-drop and the confidence interval (〈∆σ〉=0.60 (0.42-0.87) MPa and 〈∆σ〉=1.53 (1.01-2.31) for crustal and subcrustal events of Japan and 〈∆σ〉=0.36(0.30-0.44) MPa for Central Italy) show, for both regions, a self-similar, constant stress-drop scaling of the rupture duration/radius with seismic moment. The smaller sensitivity of the spatially averaged, time-varying peak displacement amplitude to the radiation from localized high slip patch on the fracture surface, could explain the retrieved smaller average stress-drops for sub-crustal earthquakes in Japan and M>5.5 events in Central Italy relative to previous estimates using spectral methods.<br><br>

scholarly journals Earthquake Seismic Moment, Rupture Radius and Stress-drop from P-wave Displacement Amplitude vs Time Curves

2021 ◽  
Author(s):  
aldo zollo ◽  
sahar nazeri ◽  
Simona Colombelli
Keyword(s):  
Stress Drop ◽  
Seismic Moment ◽  
Central Italy ◽  
Average Stress ◽  
Displacement Amplitude ◽  
P Wave ◽  
Parametric Modelling ◽  
Peak Displacement ◽  
Reliable Determination ◽  
Anelastic Attenuation

The reliable determination of earthquake source parameters is a relevant task of seismological investigations which ground nowadays on high quality seismic waveforms collected by near-source dense arrays of ground motion sensors. Here we propose a parametric modelling technique which analyzes the time-domain P-wave signal recorded in the near-source range of small-to-large size earthquakes. Assuming a triangular moment-rate function and a uniform speed, circular rupture model, we develop the equations to estimate the seismic moment, rupture radius and stress-drop from the corner-time and plateau level of the average logarithm of the P-wave displacement vs time curves (LPDT). The constant-Q, anelastic attenuation effect is accounted by a post-processing procedure that evaluates the Q-unperturbed moment-rate triangular shape.<br>The methodology has been validated through the application to the acceleration records of the 2016-2017 Central Italy and 2007-2019 Japan earthquake sequences covering a wide moment magnitude range (Mw 2.5 - 6.5) and recording distance < 100 km. After correcting for the anelastic attenuation function, the estimated average stress-drop and the confidence interval (〈∆σ〉=0.60 (0.42-0.87) MPa and 〈∆σ〉=1.53 (1.01-2.31) for crustal and subcrustal events of Japan and 〈∆σ〉=0.36(0.30-0.44) MPa for Central Italy) show, for both regions, a self-similar, constant stress-drop scaling of the rupture duration/radius with seismic moment. The smaller sensitivity of the spatially averaged, time-varying peak displacement amplitude to the radiation from localized high slip patch on the fracture surface, could explain the retrieved smaller average stress-drops for sub-crustal earthquakes in Japan and M>5.5 events in Central Italy relative to previous estimates using spectral methods.<br><br>

The RAMONES Service for Rapid Assessment of Seismic Moment and Radiated Energy in Central Italy: Concepts, Capabilities, and Future Perspectives

2021 ◽  
Author(s):  
Daniele Spallarossa ◽  
Matteo Picozzi ◽  
Davide Scafidi ◽  
Paola Morasca ◽  
Chiara Turino ◽  
...  
Keyword(s):  
Seismic Moment ◽  
Rapid Assessment ◽  
Central Italy ◽  
Web Interface ◽  
S Wave ◽  
Data Set ◽  
Decomposition Approach ◽  
Peak Displacement ◽  
Radiated Energy ◽  
Attenuation Models

Abstract We present Rapid Assessment of MOmeNt and Energy Service (RAMONES), a service for disseminating through a web interface, the estimates of seismic moment (M0) and radiated energy (ER) for earthquakes occurring in central Italy with local magnitudes above 1.7. The service is based on a fully-automatic procedure developed for downloading and processing open seismological data from the European Integrated Data Archive, Italian Civil Protection repository, and Incorporated Research Institutions for Seismology (IRIS). In its actual configuration, RAMONES uses the seismic catalog generated through the event webservice of the Italian Institute of Geophysics and Volcanology (compliant with International Federation of Digital Seismograph Networks standards) to guide the data download. The concept of RAMONES is to estimate M0 and ER from features extracted directly from recordings, namely the S-wave peak displacement (PDS) and the integral of the squared velocity (IV2S) evaluated over the S-wave window at local distances. A data set composed of 6515 earthquakes recorded in central Italy between 2008 and 2018 was used to calibrate the attenuation models relating M0 to PDS and ER to IV2S, including station corrections. The calibration values for M0 and ER were extracted from the source spectra obtained by applying a decomposition approach to the Fourier amplitude spectra known as the generalized inversion technique. To test the capabilities of RAMONES, we validate the attenuation models by performing residual analysis over about 60 earthquakes occurring in 2019 that were used for the spectral decomposition analysis but not considered in the calibration phase. Since January 2020, a testing operational phase has been running, and RAMONES has analyzed about 800 earthquakes by September 2020. The distribution of the source parameters and their relevant scaling relationships are automatically computed and disseminated in the form of maps, parametric tables, figures, and reports available through the RAMONES web interface.

Far-field pulse shapes from circular sources with variable rupture velocities

1997 ◽  
Vol 87 (5) ◽  
pp. 1288-1296
Author(s):  
Nicholas Deichmann
Keyword(s):  
Stress Drop ◽  
Seismic Moment ◽  
Total Duration ◽  
Source Model ◽  
P Wave ◽  
Far Field ◽  
Rupture Velocity ◽  
P Waves ◽  
S Waves ◽  
Rate Functions

Abstract Recently, Sato (1994) developed a simple earthquake source model of a circular rupture expanding outward from the center of a fault with constant stress drop. In contrast to previous models, the rupture velocity is allowed to vary over the duration of faulting. This model is used to synthesize apparent moment-rate functions for a three-stage source process: first, the rupture starts out with a gradually increasing velocity, then, it continues to expand uniformly until, finally, it slows to a gradual stop. Synthetic velocity seismograms are obtained from a convolution of the apparent moment-rate functions with a causal Q-operator and an appropriate instrument response. Comparisons with an example of an earthquake signal show that, in the context of the proposed model, the observed emergent P-wave onset, which is not compatible with a constant rupture velocity, can be explained by a gradually accelerating rupture front. Systematic departures from the generally expected scaling relationship between seismic moment and rupture duration are often interpreted as evidence for a dependence of stress drop on seismic moment. However, the trade-off between stress drop and rupture velocity inherent in all kinematic source models implies that such deviations can just as well be attributed to systematic variations of rupture velocity. Whereas, in general, the total duration of the far-field displacement pulse is shorter for P waves than for S waves, the model predicts that the rise time, τ1/2, of the displacement pulse should be longer for P waves than for S waves. This feature could constitute a critical test of the model and also provide a constraint on the rupture velocity.

Spectral source parameters for weak local earthquakes in the Pannonian basin

2010 ◽  
Vol 2 (4) ◽  
Author(s):  
Bálint Süle
Keyword(s):  
Stress Drop ◽  
Seismic Moment ◽  
Pannonian Basin ◽  
Source Parameters ◽  
Active Regions ◽  
P Wave ◽  
Local Earthquakes ◽  
Scaling Relationship ◽  
Dynamic Source ◽  
Relationship Of

AbstractDynamic source parameters are estimated from P-wave displacement spectra for 18 local earthquakes (1.2 < ML < 3.7) that occurred in two seismically active regions of Hungary between 1995 and 2004. Although the geological setting of the two areas is quite different, their source parameters cannot be distinguished. The source dimensions range from 200 to 900 m, the seismic moment from 6.3x1011 to 3.48×1014 Nm, the stress drop from 0.13 to 6.86 bar, and the average displacement is less than 1 cm for all events. The scaling relationship between seismic moment and stress drop indicates a decrease in stress drop with decreasing seismic moment. A linear relationship of M w = 0.71 M L + 0.92 is obtained between local magnitude and moment magnitude.

Microearthquakes and the nature of the creeping-to-locked transition of the San Andreas fault zone near San Juan Bautista, California

1984 ◽  
Vol 74 (1) ◽  
pp. 235-254
Author(s):  
William H. Bakun ◽  
Marcia McLaren
Keyword(s):  
Fault Zone ◽  
Stress Drop ◽  
Seismic Moment ◽  
Dynamic Stress ◽  
San Andreas Fault ◽  
Static Stress ◽  
P Wave ◽  
Apparent Stress ◽  
San Andreas ◽  
Static Stress Drop

Abstract Eighteen digital event recorders were deployed during May-June 1981 along the creeping-to-locked transition of the San Andreas fault zone near San Juan Bautista, California, as a supplement to the U.S. Geological Survey's central California seismic network. Analysis of 18 well-recorded microearthquakes (0.7 ≦ ML ≦ 2.8) located along the transition confirms the complexity of the crust and fault-zone structure of the transition region. Seismic-wave site amplification is 2 to 10 times greater at sites between the San Andreas and Sargent fault traces, consistent with other evidence for lower velocities in the upper 3 km of crust there. Routine mislocation of epicenters 2 to 4 km northeast of the Sargent fault are consistent with greater P-wave velocity northeast of the Sargent fault. Microearthquake source parameters are consistent with a more segmented and splayed fault geometry toward the northwest locked end of the transition. P-wave nodal planes for 10 microearthquakes located to the northwest, 9 on the Sargent fault, and 1 near the San Andreas, are oriented more westerly than nodal planes commonly obtained for the frequent moderate-size earthquakes on the creeping section of the San Andreas fault to the southeast. Static stress drop, dynamic stress drop, and apparent stress estimates all increase with seismic moment, with the apparent stress and dynamic stress drops equal to about 3 and 20 per cent, respectively of the static stress drop. Average fracture energies, calculated assuming complete stress drop, generally increase with source size (seismic moment, rupture area, seismic slip, etc.) from 7 to 3000 J/m2; the two events with anomalously low fracture energies occurred on the creeping section of the San Andreas fault.

scholarly journals Seismic Moment, Stress Drop, Strain Energy, Dislocation Radius, and Location of Seismic Acoustic Emissions Associated with a High Alpine Snowpack at Berthoud Pass, Colorado, U.S.A. (Abstract only)

1983 ◽  
Vol 4 ◽  
pp. 304-304
Author(s):  
Charles Cleland Rosé
Keyword(s):  
Stress Drop ◽  
Seismic Moment ◽  
Source Parameters ◽  
Acoustic Emissions ◽  
Body Waves ◽  
P Wave ◽  
Dissipated Energy ◽  
Fracture Area ◽  
Stress Drops ◽  
Predictive Indicator

The monitoring of the number of acoustic seismic impulses arising from snow instabilities is regarded as a relative indicator of an unstable snow slope but has not yielded a qualitative, predictive indicator. Until now, the source parameters (fracture area and length), seismic moment, energy released, stress drop, and location of acoustic seismic emissions arising from the snowpack have been neglected. A comprehension of these parameters leads to a better understanding of the event and may help in avalanche prediction.The location of a seismic event is derived from time differences between P-wave arrivals at four sensors located at the snow-ground interface. Three methods confirm the location of an acoustic seismic snow event to within 2 to 4 cm when the event is inside a seismic net.Spectral analyses of body waves from seismic snow events yield estimates of source parameters, stress drop and energy released. Equivalent dislocation surface radii range from 4.8 to 9.0 cm, which give stress drops of 0.20 to 0.29 bar, with a dissipated energy in the range of 0.0205 to 0.0632 J.Spectral analysis of the acoustic seismic snow event with application of dislocation theory provides several likely methods to predict avalanches of a climax type.

Strong-Motion Accelerograms of the Oroville, California, aftershocks: Data processing and the aftershock of 0350 August 6, 1975

1980 ◽  
Vol 70 (1) ◽  
pp. 243-267
Author(s):  
Jon B. Fletcher ◽  
A. Gerald Brady ◽  
Thomas C. Hanks
Keyword(s):  
Ground Motion ◽  
Stress Drop ◽  
Seismic Moment ◽  
Strong Motion ◽  
P Wave ◽  
S Wave ◽  
Quality Of Data ◽  
Pass Filter ◽  
Processing Scheme ◽  
Field Source

abstract The Oroville aftershock accelerograms are characterized by short durations (≲2 sec) of strong ground motion, small S-wave minus trigger times (≲2 sec), and an enrichment in frequencies above 1 Hz, as might be expected for 3 ≲ M ≲5 earthquakes recorded at close distances (R ≲ 15 km). These characteristics introduce significant error into the velocity and displacement traces calculated according to the routine procedures used in the series “Strong Motion Earthquake Accelerograms.” These errors are markedly reduced by removing all decimation in the processing scheme and by constructing a smoother response for the Ormsby high-pass filter. The result is an accurate set of velocity and displacement traces that can be used in a wide variety of source-mechanism and ground-motion studies. These revised processing procedures are applied to the ten strong-motion accelerograms of one of the largest aftershocks (0350 August 6, 1975; ML = 4.7) to illustrate the quality of data available for 12 such well-recorded aftershocks and to estimate the source properties of this particular earthquake. All of the accelerographs triggered on the P wave, allowing the recovery of the complete S wave on ten accelerograms. Offsets in displacement across the S wave and a ramp-like signature leading up to the S wave identified on the displacement traces are apparently near-field source effects. The seismic moment and stress drop determined for this normal faulting event are 4.0 × 1023 dyne-cm, and 410 bars, respectively. The seismic moment and stress drop are determined by averaging individual measurements at 9 and 8 stations, respectively, and are well-constrained with standard deviations that are about 25 per cent of the mean.

scholarly journals Seismic Moment, Stress Drop, Strain Energy, Dislocation Radius, and Location of Seismic Acoustic Emissions Associated with a High Alpine Snowpack at Berthoud Pass, Colorado, U.S.A. (Abstract only)

1983 ◽  
Vol 4 ◽  
pp. 304
Author(s):  
Charles Cleland Rosé
Keyword(s):  
Stress Drop ◽  
Seismic Moment ◽  
Source Parameters ◽  
Acoustic Emissions ◽  
Body Waves ◽  
P Wave ◽  
Dissipated Energy ◽  
Fracture Area ◽  
Stress Drops ◽  
Predictive Indicator

The monitoring of the number of acoustic seismic impulses arising from snow instabilities is regarded as a relative indicator of an unstable snow slope but has not yielded a qualitative, predictive indicator. Until now, the source parameters (fracture area and length), seismic moment, energy released, stress drop, and location of acoustic seismic emissions arising from the snowpack have been neglected. A comprehension of these parameters leads to a better understanding of the event and may help in avalanche prediction. The location of a seismic event is derived from time differences between P-wave arrivals at four sensors located at the snow-ground interface. Three methods confirm the location of an acoustic seismic snow event to within 2 to 4 cm when the event is inside a seismic net. Spectral analyses of body waves from seismic snow events yield estimates of source parameters, stress drop and energy released. Equivalent dislocation surface radii range from 4.8 to 9.0 cm, which give stress drops of 0.20 to 0.29 bar, with a dissipated energy in the range of 0.0205 to 0.0632 J. Spectral analysis of the acoustic seismic snow event with application of dislocation theory provides several likely methods to predict avalanches of a climax type.

scholarly journals Source Parameters of Moderate-To-Large Chinese Earthquakes From the Time Evolution of P-Wave Peak Displacement on Strong Motion Recordings

2021 ◽  
Vol 9 ◽  
Author(s):  
Yuan Wang ◽  
Simona Colombelli ◽  
Aldo Zollo ◽  
Jindong Song ◽  
Shanyou Li
Keyword(s):  
Stress Drop ◽  
Source Parameters ◽  
Scaling Law ◽  
Strong Motion ◽  
Early Warning Systems ◽  
P Wave ◽  
Initial Increase ◽  
Peak Displacement ◽  
Rupture Length ◽  
Plateau Level

In this work we propose and apply a straightforward methodology for the automatic characterization of the extended earthquake source, based on the progressive measurement of the P-wave displacement amplitude at the available stations deployed around the source. Specifically, we averaged the P-wave peak displacement measurements among all the available stations and corrected the observed amplitude for distance attenuation effect to build the logarithm of amplitude vs. time function, named LPDT curve. The curves have an exponential growth shape, with an initial increase and a final plateau level. By analyzing and modelling the LPDT curves, the information about earthquake rupture process and earthquake magnitude can be obtained. We applied this method to the Chinese strong motion data from 2007 to 2015 with Ms ranging between 4 and 8. We used a refined model to reproduce the shape of the curves and different source models based on magnitude to infer the source-related parameters for the study dataset. Our study shows that the plateau level of LPDT curves has a clear scaling with magnitude, with no saturation effect for large events. By assuming a rupture velocity of 0.9 Vs, we found a consistent self-similar, constant stress drop scaling law for earthquakes in China with stress drop mainly distributed at a lower level (0.2 MPa) and a higher level (3.7 MPa). The derived relation between the magnitude and rupture length may be feasible for real-time applications of Earthquake Early Warning systems.

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